[Drakelist] R4A Audio Problem.

[Curt Nixon]

I am stumped by an issue with my old trusty R4A.  The audio amp, 6EH5 
tube is running with a red-hot plate.

All of the DC voltages look good and there is no input signal except the 
real one when the gain is advanced.  There is a very large (5V P-P) on 
the output side.  It is low freq (120 hz. 

The radio has new electrolytics on main and bias supplies and I tried 
replacing the polarized tubular decoupling caps in this stage to no avail. 

I saw the note about anti-vox oscillation in the R4B tech notes and 
tried that but no change.

About the only thing I havent tried is the audio transformer.  the 
primary reads about 240 ohms. 

The audio out from the speaker is about half what it should be.

Any suggestions?

Thanks,

Curt

KU8L



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